Photoperiod as a Factor for Studying Fluctuations ofSeminal Traits during Breeding and Non-BreedingSeason

Document Type : Research Articles


Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran


The main purpose of this study was to evaluate the influence of the photoperiod on the seminal traits of crossbreed wool-producing rams throughout on year period. For the effect of photoperiod two periods were considered: decreasing daylight length (summer and autumn) and increasing daylight length (winter and spring). For the study 5 Baluchi × Moghani (BL×MG) and 5 Arkharmerino × Moghani (AM×MG) rams were used. Semen collection started from first of October 2010 to end of September 2011. After a training period of 2 weeks semen ejaculates were evaluated for volume, total sperm count per ejaculate (TSE), spermatozoa concentration, semen color, wave motion, percentage of progressive motility, percentage of live and abnormal spermatozoa, semen pH, methylene blue reduction time (MBRT) and semen index (semen volume × spermatozoa concentration/mL × live spermatozoa % × progressive motility %).Analysis of the yearlong data showed that semen samples with the best quality were collected in September to November (P<0.05). Significant seasonal variations of semen traitswere observed for all of seminal traitsexcept for progressive motility, percentage of live spermatozoa and MBRT. Yet, nostatistical differences were found between the two genetic groups (P>0.05). Although there were significant seasonal changes in semen characteristics of the crosses, the fresh semen showed adequate quality to be used for artificial or natural insemination all around the year. Photoperiod was found to influence semen production in two genetic groups at 38 ˚02' N, 46 ˚27' E at an altitude of 1567 m above sea level of Iran. However, these effects should are not detrimental to the use of rams for breeding purposes throughout the year.


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